The role of extracellular spacer regions in the optimal design of chimeric immune receptors: evaluation of four different scFvs and antigens

J Immunother. May-Jun 2005;28(3):203-11. doi: 10.1097/01.cji.0000161397.96582.59.


Human peripheral blood lymphocytes can be transduced to express antigen-dependent CD3zeta chimeric immune receptors (CIRs), which function independently of the T-cell receptor (TCR). Although the exact function of these domains is unclear, previous studies imply that an extracellular spacer region is required for optimal CIR activity. In this study, four scFvs (in the context of CIRs with or without extracellular spacer regions) were used to target the human tumor-associated antigens carcinoembryonic antigen (CEA), neural cell adhesion molecule (NCAM), the oncofetal antigen 5T4, and the B-cell antigen CD19. In all cases human T-cell populations expressing the CIRs were functionally active against their respective targets, but the anti-5T4 and anti-NCAM CIRs showed enhanced specific cytokine release and cytotoxicity only when possessing an extracellular spacer region. In contrast, the anti-CEA and anti-CD19 CIRs displayed optimal cytokine release activity only in the absence of an extracellular spacer. Interestingly, mapping of the scFv epitopes has revealed that the anti-CEA scFv binds close to the amino-terminal of CEA, which is easily accessible to the CIR. In contrast, CIRs enhanced by a spacer domain appear to bind to epitopes residing closer to the cell membrane, suggesting that a more flexible extracellular domain may be required to permit the efficient binding of such epitopes. These results show that a spacer is not necessary for optimal activity of CIRs but that the optimal design varies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, CD19 / immunology
  • Antigens, CD19 / pharmacology
  • Antigens, Neoplasm / immunology*
  • CD3 Complex / genetics*
  • CD3 Complex / immunology
  • Carcinoembryonic Antigen / immunology
  • Carcinoembryonic Antigen / pharmacology
  • Extracellular Space
  • Humans
  • Immunoglobulin Variable Region / chemistry
  • Immunoglobulin Variable Region / genetics*
  • Immunoglobulin Variable Region / immunology
  • Membrane Glycoproteins / immunology
  • Membrane Glycoproteins / pharmacology
  • Neural Cell Adhesion Molecules / immunology
  • Neural Cell Adhesion Molecules / pharmacology
  • Protein Structure, Tertiary
  • Receptors, Antigen, T-Cell / genetics*
  • Receptors, Antigen, T-Cell / immunology
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / immunology
  • T-Lymphocytes / drug effects
  • T-Lymphocytes / immunology*
  • Transfection


  • Antigens, CD19
  • Antigens, Neoplasm
  • CD3 Complex
  • CD3 antigen, zeta chain
  • Carcinoembryonic Antigen
  • Immunoglobulin Variable Region
  • Membrane Glycoproteins
  • Neural Cell Adhesion Molecules
  • Receptors, Antigen, T-Cell
  • Recombinant Fusion Proteins
  • trophoblastic glycoprotein 5T4, human